1. Field of the Invention
The present invention relates to an image processing apparatus which carries out predetermined image processing on image data having been input and outputs the image data.
2. Description of the Related Art
A flat bed type image processing apparatus is suitable for scanning an image data on a book as an original. A book is opened and placed on the flat bed with the page surface faced down, and a scanner reads an image on the flat bed. The following methods can be used to esthetically process image data corresponding to the dog-ear of the book (a book center) and an outside area of the book.
A first method according to an application filed by Riso Kagaku Corp. (Japanese Unexamined Patent Publn. No. 3(1991)-261270) carries out stencil-making based on image data of an original after placing the original on an image processing apparatus. When the original is roughly read (pre-scan), areas within and outside the original are recognized by operation on the pre-scan result. The original is then read again (main scan) and image processing is carried out on image data for the portion of the original recognized through the pre-scan.
A second method disclosed in Japanese Unexamined Patent Publn. No. 6(1994)-326865 erases a book center portion of a book form original and the area of the book center portion can be esthetically processed after only one time reading of the book form original.
In the first method, pre-scan is necessary and so is the time therefor. Furthermore, since image processing upon main scan is carried out in a state wherein areas are recognized as the same as in the pre-scan, the result of area recognition becomes useless if the position of the original is changed during the time between the pre-scan and the main scan, and improper image data are output.
In the second method, since the book center portion is erased, it is a problem that information on the book center portion is lost.
Furthermore, since a threshold value for binary conversion of character data is predetermined, a problem occurs in reproducing an original written on dark color paper or an original with faint letters.
The present invention has been created to solve the above problems. The object of the present invention is to provide an image processing apparatus whereby image data for a margin around a book form original are erased and image data for a book center portion thereof are obtained without loss. Another object is to provide an image processing apparatus which can reproduce an original written in characters more esthetically.
To achieve the above objects, an image processing apparatus of the present invention comprises binary conversion means which carries out binary conversion using a predetermined threshold value on an image signal read by original reading means;
a coercion signal generating unit which extracts a margin around an original based on the binary image signal having been binary converted by the binary conversion means; and
a character processing binary conversion unit in which a threshold value is set variably so that the portion extracted by the coercion signal generating unit is output as whitening data and the image signal of the portion other than the extracted portion is output as character data after binary conversion thereon.
Another image processing apparatus comprises first binary conversion means which carries out binary conversion using a first threshold value on an image signal read by original reading means;
a first coercion signal generating unit which extracts a margin around an original based on the binary image signals having been binary converted by the first binary conversion means;
second binary conversion means which is installed in parallel to the first binary conversion means and carries out binary conversion using a second threshold value higher than the first threshold value on the image signal read by the original reading means;
a second coercion signal generating unit which extracts a margin around the original based on the binary image signal having been binary converted by the second binary conversion means;
a character processing binary conversion unit in which a threshold value is variably set so that the portion extracted by the first coercion signal generating unit is output as whitening data and the image signal of the portion other than the extracted portion is output as character data after binary conversion thereon;
a photograph processing binary conversion unit which carries out binary conversion for photograph data on the image signal having been read by the original reading means; and
an image processing selecting unit wherein the binary converted data output from the character processing binary conversion unit and the photograph processing binary conversion unit are input and the binary converted data from the photograph processing binary conversion unit are output for an area which has been extracted by the first coercion signal generating unit and not extracted by the second coercion signal generating unit, while the binary converted data from the character processing binary conversion unit are output for the area other than the above.
The image processing apparatus may comprise character binary conversion threshold value calculating means which calculates a threshold value for outputting the image signal as binary converted character data from the character processing binary conversion means.
The first coercion signal generating unit judges a margin around an original by the output from the first binary conversion means having the first threshold value. The second binary conversion means which has the threshold value higher than the first carries out binary conversion for the area within the original including the book center portion thereof. The second coercion signal generating unit judges the area other than the margin around the original and the book center portion of the original by using the second threshold value.
Based on an logic operation result using the output signals from the first and the second coercion signal generating units, the book center portion is judged.
By using the image processing apparatus of the present invention, when an original bound as a book (a book form original) is read by a flat bed type original reading apparatus, a dog-ear portion (a book center portion) of the original which is not in contact with the original reading apparatus and the margin around the original are output after binary conversion by the photograph processing binary conversion unit and the image of the book form original can be esthetically processed.